Graphene is composed of carbon atoms, which has a structure of hexagonal lattice like honeycomb. The graphene has a thickness of one carbon atom. The graphene was discovered in 2004, and the 2010 Nobel Prize in physics was granted for this discovery. The single atom structure of the graphene results in its unique performances. For example, {circle around (1)} highly electric conductive: because electrons in the graphene almost have no quality and speed of electrons can reach 1/300 of the speed of light, the graphene has superior electric conductivity. {circle around (2)} ultra high strength:the hardness of the graphene is higher than that of diamond, and the graphene has good toughness and can be bent. {circle around (3)} large surface area:the surface area of single-layer graphene can reach to 2630 m2/g, and surface area of activated carbon is only 1500 m2/G, the large surface area makes the graphene becoming energy storage material of huge potential. Since the graphene has a number of excellent performances, research on the graphene is inspired in the worldwide.
Recently, many studies have focused on synthesis of graphene of large size in large scale. At present, the methods for making graphene can be a method of mechanical exfoliation, a method of chemical vapor deposition, a method of oxidation-reduction, a method of ultrasonic peeling, and so on. However, the graphene is easily aggregated, due to π-π conjugated effect and van der Waals forces. In addition, because of its unique structure, it is difficult to have physical or chemical action with other medium for graphene, and combining strength between the graphene and other medium is low, resulting in limit of its applications. Therefore, biggest bottleneck of application of graphene is how to obtain stable and easy dispersion of modified graphene, in order to develop its unique physical and chemical properties.